Chelsea defender Branislav Ivanovic has urged his team-mates to revive the fighting spirit that led them to Champions League glory last sesaon as they prepare to face Manchester United in the FA Cup quarter-finals on Sunday.

Ivanovic, 29, admitted Chelsea's 1-0 loss to Steaua Bucharest in the Europa League on Thursday summed up their fortunes this season but he believes the Blues should build on their disappointment rather than accepting it.

Chelsea will be aiming to keep their hopes of a fourth FA Cup trophy in seven years in tact at Old Trafford and the Serbia international is confident victory over United will be an important step to finishing the season in a positive fashion.

"We have to be honest with each other and admit that a lot of things are not going how we would like them to," Ivanovic said. "We are not playing at the level we know we are capable of and that is becoming normal for us. So we have to change things very quickly.

"Time is running out for us if we want to finish the season at the highest level. And if we want to change things we are going to have to show more character. We need to play as a team and show some fighting spirit.

"We were in the same situation last year and finished the season well. Now we have to do the same thing. But it will need real strength to do that because from now on every game for us is going to be harder and harder.

"It's not just the fighting spirit, though. There are a lot of things we need to change and that includes being honest with each other. We are 19 points behind Manchester United in the league and that gap means that we have not done well this season. That is something for everyone to think about."

Sir Alex Ferguson's side will be eager to bounce back from their Champions League departure at the hands of Real Madrid and Ivanovic believes upsets in Europe for both sides midweek will raise the stakes of their cup clash.

"It is always disappointing when you go out of the biggest competition in this way," he said. "But I think that will make them more motivated and we have to be ready for that.

"This is a big test of our character and we need to react after the defeat in Bucharest. We have had two days less to prepare for this FA Cup match than United and it is always a very physical game. But we have to recover well and be ready for the challenge.

Chelsea could fall five points behind third-placed Tottenham if Spurs beat Liverpool on Sunday, making the last automatic Champions League qualifying spot a priority for interim manager Rafa Benitez.

"We have to treat every game like a cup final," Ivanovic said. "Our supporters didn't expect to be in this situation and we must do everything we can to win something for them this season. It is a question of attitude now.

"We know United will push us from the first minute and we have to be ready for every challenge. Now is not the time to look behind and try to work out what has gone wrong. We need to look forward and believe we can have a better end to the season."